Current medical devices, such as catheters and endoscopes, are employed for the examination and/or treatment of the mammalian body. In particular, various surgical procedures employ a catheter or an endoscope to exam remote parts of the body and/or introduce surgical tools, fluids or other materials into the body for treatment thereof. For example, in some procedures, catheters and endoscopes may be used for the introduction of items including but not limited to radiographic contrast materials, drugs, angioplasty balloons, stents, fiber optic scopes, laser lights, and cutting instruments (e.g., biopsy forceps, RF cutters, atherectomy devices, etc.), into vessels, cavities, passageways, or tissues of the body.
Navigation of the catheter or endoscope through the vessels, cavities, or passageways of the body to the area of interest is critical to the success of the examination and/or treatment. To this end, modern catheters and endoscopes include an arrangement that allows the operator to deflect the distal end of an associated insertion shaft for guiding the insertion shaft through the passageways, vessels, etc., to the area of interest. For example, conventional steerable catheters and endoscopes typically comprise a control handle from which an elongated insertion shaft extends. The elongated insertion shaft is formed of a material or materials of such a stiffness so as to normally maintain the elongated shaft in a straight condition in the absence of an external force. The outer end portion of the elongated shaft is relatively flexible to permit deflection. Pairs of guide wires, also known as steering wires, are connected to the control handle, extend outwardly through the elongated shaft, and terminate at the flexible outer end portion of the elongated shaft. A guide wire control mechanism is carried by the control handle and includes a pair of rotatable control knobs that cooperate with the respective pairs of guide wires for manually controlling the angular attitude of the flexible outer end portion of the elongated tube to thereby effectively “steer” the catheter or endoscope in the up/down and right/left directions.
It is also known in the pertinent art to provide the steerable catheter or endoscope with a locking mechanism for arresting the relative deflection of the elongated shaft during use. In a conventional manner, the control knobs are manually operated to articulate the elongated shaft in four (4) directions for navigation through a vessel, cavity, or passageway of a patient. Manual release of the control knobs returns the elongated shaft to its straight condition due to the stiffness of the elongated shaft. At certain points during any particular surgical procedure, it may be desired to arrest the relative orientation of the elongated shaft. At such time, the conventional locking mechanism is activated and movement of both control knobs relative to the remainder of the catheter is simultaneously precluded. For one example of such a locking mechanism, please see co-pending application Ser. No. 11/089,380, filed Mar. 23, 2005, which is hereby expressly incorporated by reference.
While these known locking mechanisms for steerable catheters and endoscopes have proven to be acceptable for their intended applications, they are all associated with limitations. For example, it may be desirable to accomplish small positional adjustments of the elongated shaft by allowing only one control knob to effect bending at one time while the other knob is locked against rotation. Heretofore locking mechanisms, however, utilize a single locking lever to simultaneously arrest the movement of the both control knobs.
Embodiments of the present invention are directed to steering systems, and in particular, to locking mechanisms that address these limitations.